content: /*
   * Copyright 2011-2016 David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package ix;
  
  import java.util.*;
  
  final class IxToMultimap<T, K, V> extends IxSource<T, Map<K, Collection<V>>> {
  
      final IxFunction<? super T, ? extends K> keySelector;
  
      final IxFunction<? super T, ? extends V> valueSelector;
  
      IxToMultimap(Iterable<T> source, IxFunction<? super T, ? extends K> keySelector, IxFunction<? super T, ? extends V> valueSelector) {
          super(source);
          this.keySelector = keySelector;
          this.valueSelector = valueSelector;
      }
  
      @Override
      public Iterator<Map<K, Collection<V>>> iterator() {
          return new ToMapIterator<T, K, V>(source.iterator(), keySelector, valueSelector);
      }
  
      static final class ToMapIterator<T, K, V> extends IxSourceIterator<T, Map<K, Collection<V>>> {
  
          final IxFunction<? super T, ? extends K> keySelector;
  
          final IxFunction<? super T, ? extends V> valueSelector;
  
          ToMapIterator(Iterator<T> it, IxFunction<? super T, ? extends K> keySelector, IxFunction<? super T, ? extends V> valueSelector) {
              super(it);
              this.keySelector = keySelector;
              this.valueSelector = valueSelector;
          }
  
          @Override
          protected boolean moveNext() {
              Iterator<T> it = this.it;
  
              IxFunction<? super T, ? extends K> keySelector = this.keySelector;
  
              IxFunction<? super T, ? extends V> valueSelector = this.valueSelector;
  
              Map<K, Collection<V>> result = new HashMap<K, Collection<V>>();
  
              while (it.hasNext()) {
                  T t = it.next();
  
                  K k = keySelector.apply(t);
  
                  Collection<V> coll = result.get(k);
                  if (coll == null) {
                      coll = new ArrayList<V>();
                      result.put(k, coll);
                  }
  
                  V v = valueSelector.apply(t);
  
                  coll.add(v);
              }
  
              value = result;
              hasValue = true;
              done = true;
              return true;
          }
      }
  }
  